1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 // Define the necessary code and global data to look for kDebugOnStart command 6 // line argument. When the command line argument is detected, it invokes the 7 // debugger, if no system-wide debugger is registered, a debug break is done. 8 9 #ifndef BASE_DEBUG_DEBUG_ON_START_WIN_H_ 10 #define BASE_DEBUG_DEBUG_ON_START_WIN_H_ 11 #pragma once 12 13 #include "base/basictypes.h" 14 #include "build/build_config.h" 15 16 // This only works on Windows. It's legal to include on other platforms, but 17 // will be a NOP. 18 #if defined(OS_WIN) 19 20 #ifndef DECLSPEC_SELECTANY 21 #define DECLSPEC_SELECTANY __declspec(selectany) 22 #endif 23 24 namespace base { 25 namespace debug { 26 27 // There is no way for this code, as currently implemented, to work across DLLs. 28 // TODO(rvargas): It looks like we really don't use this code, at least not for 29 // Chrome. Figure out if it's really worth implementing something simpler. 30 #if !defined(BASE_DLL) 31 32 // Debug on start functions and data. 33 class DebugOnStart { 34 public: 35 // Expected function type in the .CRT$XI* section. 36 // Note: See VC\crt\src\internal.h for reference. 37 typedef int (__cdecl *PIFV)(void); 38 39 // Looks at the command line for kDebugOnStart argument. If found, it invokes 40 // the debugger, if this fails, it crashes. 41 static int __cdecl Init(); 42 43 // Returns true if the 'argument' is present in the 'command_line'. It does 44 // not use the CRT, only Kernel32 functions. 45 static bool FindArgument(wchar_t* command_line, const char* argument); 46 }; 47 48 // Set the function pointer to our function to look for a crash on start. The 49 // XIB section is started pretty early in the program initialization so in 50 // theory it should be called before any user created global variable 51 // initialization code and CRT initialization code. 52 // Note: See VC\crt\src\defsects.inc and VC\crt\src\crt0.c for reference. 53 #ifdef _WIN64 54 55 // "Fix" the segment. On x64, the .CRT segment is merged into the .rdata segment 56 // so it contains const data only. 57 #pragma const_seg(push, ".CRT$XIB") 58 // Declare the pointer so the CRT will find it. 59 extern const DebugOnStart::PIFV debug_on_start; 60 DECLSPEC_SELECTANY const DebugOnStart::PIFV debug_on_start = 61 &DebugOnStart::Init; 62 // Fix back the segment. 63 #pragma const_seg(pop) 64 65 #else // _WIN64 66 67 // "Fix" the segment. On x86, the .CRT segment is merged into the .data segment 68 // so it contains non-const data only. 69 #pragma data_seg(push, ".CRT$XIB") 70 // Declare the pointer so the CRT will find it. 71 DECLSPEC_SELECTANY DebugOnStart::PIFV debug_on_start = &DebugOnStart::Init; 72 // Fix back the segment. 73 #pragma data_seg(pop) 74 75 #endif // _WIN64 76 77 #endif // defined(BASE_DLL) 78 79 } // namespace debug 80 } // namespace base 81 82 #endif // defined(OS_WIN) 83 84 #endif // BASE_DEBUG_DEBUG_ON_START_WIN_H_ 85